NOM & REV?

[NeonAtron]

i have a switch on my sub for NOM OR REV. dont know what it means or what it does. can anybody help me?

[TFFantasy44]

I'm guessing that's a phase control, it'd be just like switching the + and -

[KMoney28]

I'm not sure what it does exactly, but I remember some time back someone told me that the REV function is bad for the subs, and to always leave it at NOM. So that's what I've done, sound wise it sounds the same.

[Navy I.C.]

don't worry about damage,
rev will have your subs pushing at a certain time or if you have it on nom it will pull instead...
as for the sound, that's a matter of personal taste.

[CBFryman]

Originally Posted by Navy I.C.

don't worry about damage,
rev will have your subs pushing at a certain time or if you have it on nom it will pull instead...
as for the sound, that's a matter of personal taste.

all speaker push and pull....it switches the (+) with the (-) terminal outputs to match seperate amps one different speakers...its to keep out of fase speakers from canceling each other out....

[PaulD]

when you mount subs in the rear and mids/hi's in the front, you can cause phase problems. The switch, as most of you have already figured out, reverses the + and - ... which is the same as changing the phase of the subs by 180 deg. The best thing to do is see what is sounds like in both position.

P.S. It changes both channels on the amp at the same time, so it will NOT prevent subs that are wired up differently from each other from cancelling each other out.

[Navy I.C.]

Originally Posted by CBFryman

all speaker push and pull....it switches the (+) with the (-) terminal outputs to match seperate amps one different speakers...its to keep out of fase speakers from canceling each other out....

depending on acoustics (absorbed, directed and reflected sounds), in phase speakers can create holes (cancellation) and out of phase could possibly reinforce some applications. it's all about your app. and your acoustics.

little experiment for you...

put a 9volt battery on to your speaker (old speaker) leads for a second (+ to + and - to -)...
notice if your speaker pushes out or pull in...
now, switch the leads...
notice how your speaker changed the direction of it's movement...
what did we learn?
speaker movement is determined by the current phase of the input signal (20hz = 20 cycles)...
what does it mean?
This mean you should give both ways a try and choose what sounds better to you, because some speakers may sound different depending on the way your listening environment acoustics react to sound.

[CBFryman]

Originally Posted by Navy I.C.

depending on acoustics (absorbed, directed and reflected sounds), in phase speakers can create holes (cancellation) and out of phase could possibly reinforce some applications. it's all about your app. and your acoustics.

little experiment for you...

put a 9volt battery on to your speaker (old speaker) leads for a second (+ to + and - to -)...
notice if your speaker pushes out or pull in...
now, switch the leads...
notice how your speaker changed the direction of it's movement...
what did we learn?
speaker movement is determined by the current phase of the input signal (20hz = 20 cycles)...
what does it mean?
This mean you should give both ways a try and choose what sounds better to you, because some speakers may sound different depending on the way your listening environment acoustics react to sound.

lmao this is funny because DC current will only make it push or pull where as AC current will make it go in both directions....key term AC...alternating current...push, pull, push, pull, push, pull, push, pull....as the cycle continues....out of phase woofers rarely re enfoce each other except for in a seal enclosure where bother speakers share the enclosure but fire into different baffles....where basicly being out of phase makes one speaker push the other as it is pulling while the speaker that is being pushed is also pushing....but the same results can be aceived by setting up 2 woofers isobaicly...and if the two speakers happen to have a sound leak between them then wave cancleation begins to occur if there isnt enough delay.
as for the nom rev making it sound differnt acoutic wise it does little if all speakers are already in phase with each other...because whether a speaker starts is cycle pulling or pushing makes little difference to the ear...

[Navy I.C.]

hey neon, the answer to your question is try both ways, and see what sounds best to you...

as for the fried cb man/guy, i got a question for you. is it possible for the reflected sound of a set of in-phase speakers to create holes in the directed sound...?

[CBFryman]

i beleive so...depends on the delay of the woofer(s) but im not completely sure...

[Navy I.C.]

knowing that, you can expound on that theory by
saying something like reflected sounds(waves) can
reinforce and/or cancel out other waves depending on
the acoustical environment...

[CBFryman]

well like i said it depends on how long the wave is delayed...since sound waves are compression waves and not transient (sp?) waves it where a wave is canceled out or reinforced depends on whether the waves are both at a low pressure peak or both at a high pressure peak...or if one is at a high pressure and one is at a low pressure....if one is at a high and hte other a low when they meet there will be cancelation...if both at at a high there will be reinforcement.... also different frequincies will cancel out other frequincies where as some frequincies will re enforce others....it depends on their note and which octave they are in...different frequincies canceling or reinfoceing one another causes distortion....this distortion is called harmonics...some rooms will cause holes in higher frequincies near the walls because delay on them is smaller and the fact that there are so many more peaks per second for distortion to occur makes them more suseptable where as they will be reenforced nearer to the center where as lower (bass frequincies) ones are often re enfoced in corners and along walls and canceled nearer to the center of a space....the perfect acoustical environ ment is one where there is no where for the sound to reflect and cause holes or peaks...but since no one wants to watch a movie outside baffles can be used....baffles are sound canceling devices that allow waves to come in but not escape...basicly a dead end for compression waves....this may not be 100% corect but the basis of the idea is there

[Navy I.C.]

i didn't mean to literally expound on what i was saying but, i guess you kinda get the idea. now you should try translating it to normal english for neonatron...

[PaulD]

Originally Posted by CBFryman

well like i said it depends on how long the wave is delayed...since sound waves are compression waves and not transient (sp?) waves

WOW, MUSIC ISN'T TRANSIENT - I GUESS IT MUST BE STEADY STATE

it where a wave is canceled out or reinforced depends on whether the waves are both at a low pressure peak or both at a high pressure peak...

WHAT DETERMINES WHETHER A WAVE IS CANCELLED OR REINFORCED IS DISTANCES, SO IT'S FREQUENCY DEPENDENT

or if one is at a high pressure and one is at a low pressure....if one is at a high and hte other a low when they meet there will be cancelation...if both at at a high there will be reinforcement....

I THINK YOU ARE CONFUSING PRESURE NODES AND FREQUENCY DEPENDENT CANCELLATIONS

also different frequincies will cancel out other frequincies where as some frequincies will re enforce others

NOOOO ...... THE ONLY THING THAT CAN CANCEL OUT A FREQUENCY IS TWO SPEAKERS PLAYING THAT SAME FREQUENCY OUT OF PHASE WITH EACH OTHER

....it depends on their note and which octave they are in...different frequincies canceling or reinfoceing one another causes distortion....this distortion is called harmonics

NO, BY IT'S VERY NATURE HARMONIC DOSTORTION IS A DISTORTION OF THE HARMONICS (MULTIPLES OF THE FUNDAMENTAL TONE). THE DISTORTION THAT IS CAUSED BY ADDING OR SUBTRRACTING OF TWO FUNDAMENTAL TONES IS CALLED INTERMODULATION DISTORTION

...some rooms will cause holes in higher frequincies near the walls because delay on them is smaller and the fact that there are so many more peaks per second for distortion to occur makes them more suseptable where as they will be reenforced nearer to the center where as lower (bass frequincies) ones are often re enfoced in corners and along walls and canceled nearer to the center of a space....

DON'T KNOW ENOUGH ABOUT IT TO EVEN SPECULATE

the perfect acoustical environ ment is one where there is no where for the sound to reflect and cause holes or peaks...but since no one wants to watch a movie outside baffles can be used....baffles are sound canceling devices that allow waves to come in but not escape...basicly a dead end for compression waves....this may not be 100% corect but the basis of the idea is there

I THINK THE CONCEPT HE IS REFERRING TO IS "LEDE" OR LIVE END DEAD END. YOU PUT SONEX, A SOUND ABSORBING MATERIAL FOUND IN RECORDING STUDIOS, ON THE HALF OF THE ROOM THAT THE SPEAKERS ARE IN - THEN PUT NOTHING (BARE WALLS) ON THE OTHER HALF, THE LISTENING END. THIS CAUSES MOST OF THE EARLY REFLECTIONS OFF OF WALLS, FLOOR AND CEILING TO BE BE NEGATED. IN THE CAR STEREO WORLD, WE DO THIS BY MOUNTING MID/TWEETS IN THE KICK PANELS.

I really wanna know what this guy has been reading .... sounds like he's gotten a hold of a bunch of sales literature written by marketing engineers. Most of it, it's so convoluted, I can't make heads or tails of it. And just for the record, that switch STILL changes the phase of BOTH subs at the same time - so you will NOT get box cancellations in either position.

[CBFryman]

never said it would unless the woofers are wired un phased